Spring-blooming perennials, especially in the bare root form, are best planted early in the fall. Planting in the fall while the soil is still warm will give the roots enough time establish properly. This allows the plants to emerge from well established roots, with a stronger start, the following spring.
Although each plant's needs may vary and some will be more winter-hardy than others, in general about a month before the last fall frost is sufficient in giving the plant enough time to establish itself and take root.
Late summer and fall are ideal times to plant perennials that flower in spring and early summer. When you plant in the fall, early-season bloomers have a chance to built root systems and establish vigor -- which will show up in the following year's bloom.
Planting. Most perennials should be planted in the fall or early spring. Fall planting gives the plant more time to become established before the start of active growth in the spring. Fall-planted perennials are usually well-established before hot weather.
Perennials can be planted any time of year.
By planting them in the fall, plants will have a long time to establish a strong root system before the hot, dry summer months. In fact, the roots are likely to continue to grow as long as the soil temperature is over 50 degrees Farenheit.
The newly emerged growth of most perennials can tolerate temperatures in the low 30s and upper 20s Fahrenheit. Freeze damage may occur if temperatures drop into the lower 20s or teens. Most well-established perennials that have been damaged by freezing temperatures should survive.
Perennials are slow growers at first: They take the first one to three years to establish deep roots and dense foliage. However, once established, they thrive with little maintenance to give your yard beautiful new growth year after year.
By dividing the plant when it is not flowering, all the plant's energy can go to root and leaf growth. Fall division should take place between early September in the uppermost Piedmont and mid- to late October on the coast. Allow at least four to six weeks before the ground freezes for the plants to become established.
Plant Flowers and Vegetables
If you live in a frost-free region, October is a great time to plant cool-weather flowers and vegetables in your garden. Crops such as kale, cabbage, collards, lettuce, carrots, mustard, onions, Brussels sprouts, cauliflower, beets, and garlic can all be planted in early to late October.
Root vegetables: Plant beets, radishes, carrots, parsnips, turnips, and rutabaga from seed this month. For a colorful harvest, try Golden, Bull's Blood, and Chioggia beets and white, red, purple, and pink radish varieties. Carrots also come in a variety of colors, including yellow, maroon, and several shades of orange.
Transplant perennials when the weather is cool, even a little rainy, if possible. Early spring and fall care are best times for transplanting. Then the weather is cooler and the plants are not using as much water. “However, don't move or transplant perennials while they are in bloom,” he says.
Some perennials, like hostas, peonies and daylilies, need to be pruned in fall to avoid winter damage. Plants like these should be pruned after the first few frosts in late fall or early winter. Other perennials like mums and coneflowers are better off being pruned in spring just before new growth comes in.
Some Plants Are Especially Cold Hardy
Many cold hardy perennials, shrubs and trees are excellent candidates for fall planting. In general, plants with USDA cold hardiness ratings of 3, 4 and 5, are the best candidates for fall transplanting in cold winter climates.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
While not all perennials need time to look and do their best, this is a common enough phenomenon that there is an actual adage for it "The first year they sleep, the second year they creep and the third year they leap!" But what does that really mean?
It's common to think that everything should be chopped down to the ground in the fall, but some perennials actually need their foliage to protect new shoots through the winter. Other varieties offer up important habitat for local wildlife and some perennials provide height and interest through the winter months.
Spring Perennial Plantings:
Week 1: Every day to every other day. Weeks 2-3: Water 2-3 times per week, depending on environmental conditions. Weeks 4+: Water 2-3 times per week, more in hot/dry conditions.
Bulbs and perennials emerging from the ground do not need to be protected from sub-freezing temperatures. They are growing according to nature's schedule. You don't need to protect plants until after we've had an extended warm period.
1. In order to overwinter a perennial or shrub in a container outside, it needs to be two zones hardier than the zone you live in. 2. Perennials and shrubs that are in your zone or one colder can be overwintered in an unheated garage, buried in the ground, or transplanted.
A hard freeze in May is not uncommon for some areas and can kill tender perennials. Hardy plants such as daylilies, hosta, peonies, lily-of-the-valley will survive a late spring frost, but they will be out of commission until warmer weather returns.